A technology of acquiring a three-dimensional image using a capturing device is advancing. Depth information (depth map) is required for acquiring a three-dimensional image. Depth information is information that indicates a spatial distance and shows perspective information of a point with respect to another point in a two-dimensional image.
A method in which infrared (IR) structured light is projected to an object and light reflected from the object is interpreted to extract depth information is one of the methods of acquiring depth information. According to the method using the IR structured light, there is a problem in that it is difficult to obtain a desired level of depth resolution for a moving object.
A time-of-flight (TOF) method is gaining attention as a technology for substituting the method using IR structured light. According to the TOF method, a distance from an object is calculated by measuring a flight time, i.e., a time taken for emitted light to be reflected.
Generally, a camera according to the TOF method (hereinafter, a TOF camera) includes a scanner that adjusts the angle of light directed toward an object and a mirror that adjusts the optical path. Since light has to be reflected multiple times in the TOF camera, there are problems in that the structure is complicated and implementing in a small size is difficult. In addition, although a refractive index of light output from a light source has to be adjusted with a rapid response speed for the scanner to scan a front surface of an object, there is a technical limitation for the scanner to have a rapid response speed.